At one particular moment, a 19.0 kg toboggan is moving over a horizontal surface of snow at 4.00 m/s. After 7.00 s have elapsed, the toboggan stops. Use a momentum approach to find the magnitude of the average friction force (in N) acting on the toboggan while it was moving.

10.86 N

Explanation:

Let the average frictional force acting on the toboggan be 'f' N.

Given:

Mass of toboggan (m) = 19.0 kg

Initial velocity (u) = 4.00 m/s

Final velocity (v) = 0 m/s

Time for which friction acts (Δt) = 7.00 s

Now, change in momentum is given as:

Now, we know that, change in momentum is equal to the impulse acting on the body. So,

Impulse is,

Now, we know that, impulse is also given as the product of average force and the time interval for which it acts. So,

Rewriting the above equation in terms of 'f', we get:

Plug in the given values and solve for 'f'. This gives,

Therefore, the magnitude of frictional force is

magnityde and direction